Probing method and device

ABSTRACT

A probing device for inspecting semiconductor devices such as IC chips includes a mounting section for supporting a silicon substrate wafer (i.e., an object to be inspected), a moving section for moving a probe card in such a way that contacts formed on a surface of the probe card can be pushed against electrode pads formed on the wafer, and a measuring section. The probe card is formed by joining a silicon nitride (Si 3  N 4 ) thin film (whose thermal expansion coefficient is roughly equal to that of the silicon wafer) to a lower surface of a wiring substrate. The wiring substrate is composed of a polyamide thin film (as an insulating layer) and conductive layers (as conductive signal line paths) formed in and on both the surfaces of the polyamide thin film. Further, bumps (contacts) are arranged on the lower surface of the silicon nitride thin film. A plurality of through holes are formed penetrating from the upper surface of the wiring substrate to the lower surface of the silicon nitride film at an area outside the bump arrangement region. These through holes mechanically connect the silicon nitride thin film to the wiring substrate and further electrically connect the bumps to the circumferential portion of the probe card body via the conductive layers. Since the thermal expansion coefficient of the silicon wafer is roughly equal to that of the silicon nitride thin film of the probe card, even when the silicon wafer is heated or cooled for electrical measurements, it is possible to securely keep contact between the contacts (bumps) of the probe card and the electrode pads formed on the IC chips of the wafer without dislocation.

BACKGROUND OF THE INVENTION

The present invention relates to a probing method and a probing devicesuitable for use to test semiconductor devices such as IC chips formedon a silicon wafer.

In the manufacturing process of semiconductor devices, after a waferprocess has been completed and further IC chips have been completelyformed in a silicon wafer, electrical measurements (termed probe test)are effected to examine the presence or absence of shorts ordisconnections in formed electrode patterns and the input and outputcharacteristics of the completed IC chips. That is, the acceptance orrejection of the IC chips is discriminated with respect to quality underthe condition of the semiconductor wafer (referred to as wafer,hereinafter). After that, the wafer is divided into a plurality of ICchips. Further, the accepted IC chips are packaged, and furthersubjected to a handler test as to other items to finally determine theacceptance or rejection of the IC chip products.

In the probing device as described above, a wiring substrate (termedprobe card) provided with a plurality of needles is used. This probecard has an insulating substrate, on one surface of which a group ofcontacts is arranged. Further, a plurality of needles (probes) made oftungsten, for instance, are provided on the insulating substrate. Oneend of each needle is connected to one of the contacts and the other endof each needle extends obliquely from the other surface of theinsulating substrate. For an electrical test or inspection, contactsformed in the probe card are electrically connected to electrodes of atest head, and further the needles (probes) are brought into contactwith electrode pads formed on the IC chips by moving a wafer mountingbase for position matching between the needles and the electrode pads.After that, high frequency test signals equivalent to the operationalspeed of the IC chips are inputted to the IC chips from the test headthrough the probe card, and further the test signals outputted from theIC chips are returned to the test head, to electrically test the ICchips on the basis of the signals outputted by the IC chips to betested.

By the way, recently there exists such a tendency that the semiconductordevices have been microminiaturized and highly integrated more and more,so that the electrode pads of the IC chips are being miniaturized andfurther the arrangement pitch of the electrode pads is being reducedmore and more. At present, the size of the electrode pads is about 70 μmon one side thereof and the tip diameter of the needle is about 30 μm.However, when the electrode pads are further miniaturized and therebythe pitch thereof is further reduced, it is extremely difficult toarrange the needles so as to be brought into contact with the electrodepads.

To overcome the above-mentioned problem, the inventor is now studyingthe method of forming the probe card as follows: a flexible thin filmformed of polyamide resin is used; conductive projections (referred toas bumps) formed of gold 18 carats fine or copper, for instance, arearranged as contacts or needles on one surface of the this flexiblefilm; and a wiring multilayer, connected to the bumps, respectively isformed inside the flexible thin film.

In the probe card formed as described above, it is possible to formmicrominiaturized bumps on the insulating substrate according to apredetermined arrangement pattern in accordance with the printingtechnique.

On the other hand, in the case of the burn-in test for previouslydetecting defective IC chips under severer conditions than usual, the ICchips are so far tested after having been packaged. Recently, however,it has been studied to conduct the burn-in test of the IC chips underthe conditions of the wafer. In this case, a temperature adjuster isincorporated in the wafer mounting base, and the wafer is tested underthe condition that the test temperature is adjusted within such a widerange as between -40° and +150° C., for instance.

In the case of the above-mentioned probe card, however, since thereexists a big difference in coefficient of thermal expansion between theflexible thin film resin (e.g., polyamide, 3.1×10⁻⁵) and the siliconwafer (2.42 ×10⁻⁶), in such a sever and wide temperature test from roomtemperature to 100° C. or higher as described above, the matchingpositions of the bumps relative to the electrode pads as adjusted atroom temperature are easily dislocated markedly within the largetemperature range. The change rate of the matching positions between thebumps and the electrode pads increases with increasing area of thewafer, that is, with increasing wafer diameter.

Therefore, even if the bumps are formed on the flexible thin film so asto confront the electrode pads arranged on the wafer at roomtemperature, since the size of the electrode pads is extremely small andin addition the pitch of the electrode pads is narrow (with the resultthat the bump size is reduced to that extent), the electrical contactconditions between the bumps and the electrode pads are deteriorated, orthe pumps are easily dislocated from the electrode pads at the worst atanother higher or lower temperature. In other words, even if the methodof forming bumps on the thin film is adopted, there still exists aproblem in that it is impossible to perform the test reliably by use ofa probing device, due to the recent advance of the device integrationrate, microminiaturization, and wafer diameter.

SUMMARY OF THE INVENTION

With these problems in mind, therefore, it is the object of the presentinvention to provide a probing method and a probing device, by which thecontacts (bumps) of a probe card can be reliably kept in contact withthe electrode pads of silicon substrate to be tested (an object to beinspected) during electrical test under the conditions that the objectto be tested is kept cooled or heated.

To achieve the above-mentioned object, a probing method according to thepresent invention comprises the steps of: preparing a probe card formedwith contacts; connecting the contacts with measuring means; preparingan object to be inspected of silicon substrate having electrode pads;pushing the probe card against the inspected object to bring thecontacts into contact with the electrode pads of the inspected object;heating or cooling the inspected object; and measuring the inspectedobject eclectically by the measuring means, characterized in that theprobe card is formed of silicon nitride on at least one surface sidethereof facing the inspected object.

Further, a probing device according to the present invention comprises:inspected object mounting means for supporting an object to be inspectedof silicon substrate having electrode pads; measuring means; a probecard having contacts electrically connected to said measuring means andarranged so as to face the inspected object; means for moving said probecard relative to the inspected object so that the contacts can bebrought into contact with the electrode pads of the inspected objectmounted on said inspected object mounting means; means for heating orcooling the inspected object; and wherein said probe card is formed ofsilicon nitride on at least one surface thereof facing the inspectedobject.

In the probing method and device according to the present invention,since the thermal expansion coefficient of the silicon wafer is almostequivalent to that of the silicon nitride, even when the probe card isbrought into contact with an object to be inspected (i.e., a siliconwafer) and further the silicon wafer is heated or cooled, it is possibleto keep the matched positions between the probe card and the siliconwafer as adjusted at room temperature, with the result that it ispossible to allow the bumps (contacts) to accurately keep contact withthe miniaturized electrode pads arranged on the semiconductor wafer atan extremely small pitch.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front, partially cross-sectional, view showing an embodimentof the probing device according to the present invention;

FIG. 2 is an enlarged partially cross-sectional view showing the probingdevice shown in FIG. 1, together with a probe card;

FIG. 3 is an enlarged cross-sectional view showing a modification of theprobe card shown in FIG. 2;

FIG. 4 is a front, partially cross-sectional view showing anotherembodiment of the probing device according to the present invention;

FIG. 5 is an enlarged partially cross-sectional view showing the probingdevice shown in FIG. 4, together with a probe card and intermediateconnecting bodies;

FIG. 6 is a perspective, partially broken, view showing a part of theprobing device shown in FIG. 5;

FIG. 7 is a front, partially cross-sectional, view showing anotherembodiment of the probing device according to the present invention;

FIG. 8 is an enlarged perspective view showing a mechanism shown in FIG.7;

FIG. 9A is an illustration showing one shape of the bumps; and

FIG. 9B is an illustration showing another shape of the bumps.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1, on a wafer mounting base 1, a heater 11 and temperatureadjusting means (not shown) including a cooling medium (refrigerant)passage are arranged. Therefore, the temperature of a wafer W can beadjusted within a range from -40° to +150° C. Further, the wafermounting base 1 is so constructed as to be moved finely in three axialdirections: for instance, X direction in the horizontal plane, Ydirection perpendicular to the X direction in the same horizontaldirection, and 8 direction about a vertical axis, with a drivingmechanism 12. In addition, the wafer mounting base 1 is so constructedso as to be moved in the vertical direction between a wafer inspectionposition and a wafer mounting and dismounting position.

Over the wafer mounting base 1, a circular probe card 2 is provided soas to confront the wafer mounting base 1. The probe card 2 is supportedby a supporting member 13 at the lower circumferential surface thereof.As depicted in FIG. 2, the probe card 2 has a card body 20. This cardbody 20 is a flexible insulating substrate formed of polyamide thinfilm, for instance. In this insulating film, there are formed a wiringsubstrate 3 for forming a conductive layer (described later) and asilicon nitride (Si₃ N₄) thin substrate 4 formed on the wafer side (thelower side in FIGS. 1 and 2) of the wiring substrate 3. Further,contacts such as bumps of conductive projections 41 are arranged on thelower surface of the Si₃ N₄ thin substrate 4. These bumps 41 arearranged in corresponding positional relationship with respect to allthe electrode pads, so as to be simultaneously brought into contact withthe electrode pads of all the IC chips formed on the wafer W. Thesebumps 41 are formed of gold of 18 carats fine, tungsten, or nickelalloy, for instance.

Further, the card body 20 is formed with signal line through holes orshort via holes 21 penetrating from the one surface to the other surfaceof the card body 20, that is, from the upper surface of the wiringsubstrate 3 to the lower surface of the Si₃ N₄ thin substrate 4 andarranged in an outer area outside the bump (41) arrangement region. Theholes 21 may be solid instead of being hollow.

The number of these through holes 21 is equal to or more than that ofthe bumps 41. On the lower surface of the Si₃ N₄ thin substrate 4, aconductive layer 42 with a thickness of about 20 μm and made of copperor gold is formed to form signal line conductive paths between theexposed ends of the through holes 21 and the bumps 41, respectively. Inaddition, the probe card 2 or the card body 20 is formed with connectingthrough holes 22, in the same way as the through holes 21, penetratingfrom the upper surface to the lower surface of the card body 20 andarranged at the outer circumferential portion thereof. These throughholes 21 and 22 are electrically connected to each other via aconductive layer 31 formed inside the wiring substrate 3. Here, it ispossible to form a great number of conductive lines on this singleconductive layer 31 (as shown in FIG. 2) by reducing the line width asmuch as possible. However, when the number of the bumps 41 is so largethat the conductive lines cannot be formed on a single layer, theconductive layer 31 is formed as a multilayer to increase the number ofthe conductive lines for connecting these through holes 21 and 22.

Further, on both surfaces of the card body 20, grounding layers 30 and40 made of copper foil, for instance is formed apart from the throughholes 21 and 22 and conductive layer 42, in such a way as to surroundthese through holes and conductive layer. These grounding layers 30 and40 are electrically connected to a grounding through hole (not shown)formed in line with the connecting through holes 22, via a ground layer32 formed on the lower surface of the wiring substrate 3, for instance.This grounding through hole is grounded via an intermediate connectingbody and a performance board of a test head (described later).Accordingly, the signal line conductive paths can be electricallyshielded by these grounding connection. Further, the thickness of thewiring substrate 3 and the Si₃ N₄ thin substrate 4 is on the order ofabout several hundred microns, respectively. Further, in thisembodiment, the wiring substrate 3 and the Si₃ N₄ thin substrate 4 areboth fixed locally by these through holes 21 and 22, respectively.

As shown in FIG. 1, an annular intermediate connecting body 5 isarranged over the probe card 2. Further, over the intermediateconnecting body 5, a test head 6 having a wiring substrate 61 at thelower surface side thereof is arranged as a part of the measurementsection. At the circumferential portion of the intermediate connectingbody 5, conductive axles (referred to as pogo pins) 51 always urged inthe projecting direction are provided so as to project upward anddownward at the positions corresponding to the connecting through holes22. The lower ends of these pogo pins 51 are in contact with the upperends of the through holes 22 and the upper ends of these pogo pins 51are in contact with the contacts (not shown) of the wiring substrate 61of the test head 6, respectively. As described above, the bumps 41 ofthe probe card 2 are electrically connected to the test head 6 by way ofthe conductive layers 42 and 31 formed in the probe card 2, the throughholes 21 and 22 and the intermediate connecting body 5.

Further, a damping body 52 (e.g., an air mat or a rubber body) ofcompressive state is interposed in the central space of the annularintermediate connecting body 5, that is, between the probe card 2 andthe wiring substrate 61 of the test head 6, so that the card body 20 canbe pressed in the downward direction thereof.

The function of the above-mentioned embodiment of the probing deviceaccording to the present invention will be described hereinbelow. First,an object to be inspected of silicon substrate (e.g., wafer W) ismounted on the wafer mounting base 1. After that, an optical positiondetecting instrument (not shown) is inserted between wafer mounting base1 and the probe card 2, and further the wafer mounting base 1 is movedin the three directions of X, Y and θ, respectively with the use of thedriving mechanism 12 to adjust the position of the wafer W relative tothe probe card 2 for position matching. Successively, the wafer mountingbase 1 is raised to bring all the electrode pads of all the IC chipsformed on the wafer W into contact with the bumps 41 arranged on theprobe card 2 simultaneously. In this case, since the bumps 41 can beconnected to the chip electrode pads under the urged conditions causedby a restoring force of the damping body 52, it is possible to realize areliable electrical contact between the bumps 41 and the electrode pads.After that, the heater 1 is turned on to heat the wafer W up to 80° to150° C., for instance. Further, predetermined test pulse signals areapplied from the test head 6 to the IC tips on the wafer W, and the testpulse signals transmitted from the IC chips are returned to the testhead 6, in order to discriminate whether the IC chips are acceptable ornot.

In the above-mentioned embodiment, since the wafer W is located in aclose vicinity of the probe card 2, heat of the wafer W is inevitablytransmitted from the wafer W to the probe card 2 directly via the bumps41 or indirectly by radiation. Therefore, the temperature of the probecard 2 reaches almost the same temperature as that of the wafer W. Inthis embodiment, however, since the coefficient of the thermal expansionof the silicon is 2.42×10⁻⁶ and that of the Si₃ N₄ thin substrate 4 is2.5×10⁻⁵ ; that is, there exists no big difference between the two, thesilicon wafer W and the Si₃ N₄ thin substrate 4 expand due to heat bothat almost the same rate. Further, although the wiring substrate 3 formedon the Si₃ N₄ thin substrate 4 is a polyamide film and therefore thecoefficient of the thermal expansion of this polyamide is 3.1×10⁻⁵(which is larger than that (2.42×10⁻⁶) of the Si₃ N₄ thin substrate 4),since the polyamide wiring substrate 3 is locally fixed to the Si₃ N₄thin substrate by the through holes 22 and 24 respectively, even if thewiring substrate 2 is deformed into a convex shape in the upwarddirection, the Si₃ N₄ thin substrate 4 is not subjected to the influenceof distortion of the polyamide film 3 due to the difference in thermalexpansion coefficient between the two 3 and 4.

Accordingly, the dislocation rate of the electrode pads on the wafer Wis almost equivalent to that of the bumps 41 on the probe card 2. As faras the probe card position is adjusted relative to the wafer position atroom temperature, even after the wafer and the probe card, brought intocontact with each other, have been heated together up to a hightemperature, it is possible to keep the reliable mutual positionalrelationship with respect to each other. Therefore, even if the minuteelectrode pads are arranged on the wafer W at an extremely small pitch,it is possible to keep the contact between the electrode pads and thebumps under an accurate positional condition. As a result, the probingdevice according to the present can cope with the higher integration andhigher microminiaturization of the wafer W. In addition, since thedislocation between the electrode pads and the bumps is small evenwithin a wide inspection area, it is possible to cope with the largerdiameter of the wafer W. Further, when the probe card 2 is composed ofthe wiring substrate 3 and the Si₃ N₄ thin substrate 4, there existssuch an advantage that it is possible to freely select the thin filmmaterial of the wiring substrate 3 so as to be suitable for the singlelayer or the multilayer (a polyamide film is used in the above-mentionedembodiment).

Further, in this embodiment, it is also possible to provide thetemperature adjusting means including the heater on the probe card side.In this case, the positions of the wafer W and the probe card 2 arematched with respect to each other, under the conditions that both areheated (or cooled) independently.

Further, in the above-mentioned embodiment, the conductive layers 31 and42 are formed on both sides of the probe card substrate (the films 3 and4 in FIG. 2) as the conductive paths of the probe card 2. Without beinglimited thereto, however, it is also possible to form the conductivepaths from the bumps 41 to the intermediate body 5 by use of only theprinted wires formed on the surface of the probe card substrate and thethrough holes.

FIG. 3 shows another embodiment as described above. In this embodiment,the substrate of the probe card 2 itself is formed of only a Si₃ N₄ thinfilm 70; the respective bumps 41 are formed at the lower ends of thethrough holes or short via holes 71 for signal lines; and conductivepaths 73 are formed by printed wires extending from the through holes 71to connecting through holes 72 formed at the circumferential portion ofthe probe card 2. In FIG. 3, the grounded layers are denoted by 74 and75, respectively. In this embodiment, since the wafer W and the probecard 2 expand to the same extent at the high temperature, it is possibleto obtain the same function and the same effect as already explainedabove with reference to FIGS. 1 and 2.

In the probing device according to the present invention, without beinglimited to only the high temperature test, the same effect can beobtained even at the low temperature test. Further, without beinglimited to only the above-mentioned embodiment in which the bumps arearranged so as to be brought into contact with all the electrode pads ofall the IC chips formed on the wafer, it is also possible to arrange thebumps in correspondence to the electrode pads of a single IC chip or aplurality of IC chips formed on the wafer.

Further, with respect to the connection between the probe card and thetest head, without use of the annular intermediate connecting body, itis also possible to adopt such a structure that a plurality ofconnecting through holes are formed at the circumferential portion ofthe probe card (as in the above-mentioned embodiment); the bumps(contacts) are formed on the upper or lower ends of the connectingthrough holes; and the bumps are connected to a connector attached to anend of a cable extending from the test head. Further, it is alsopossible to use a flat connector terminal mated with the circumferenceof the probe card.

As described above, in the probing device according to the presentinvention, in order to effect the electrical test of an object (siliconsubstrate) to be inspected, the substrate formed on at least theinspected object side of the probe card is made of Si₃ N₄ whose thermalexpansion coefficient is almost equivalent to that of the silicon, whenthe inspected body and the probe card are heated or cooled, the mutualpositional dislocation of the contacts (bumps) formed on the probe cardside relative to the electrode pads formed on the inspected object canbe minimized, with the result that it is possible to securely keepcontact between the electrode pads and the probe card contacts, even ifthe minute electrode pads are arranged on the inspected object at asmall pitch.

By the way, at the connecting portion between the probe card 2 and thewiring substrate 61 of the test head 6; that is, at both contact ends ofthe pogo pins 51, the signal terminals and the grounding terminals mustbe kept away from each other, so that appropriate gaps must be formedbetween the two, with the result that a high impedance portion isinevitably formed at these portions.

On the other hand, recently there exists such a tendency that the deviceintegration rate and the device operating speed have been both increasedmore and more, so that it is expected that the frequency of the devicetesting signals increases up to as high as 1 GHz. Therefore, in the casewhere the impedance of the conductive paths relative to the ground ishigh, since the waveforms of the test pulse signals are distorted, thereexists a problem in that a precise electrical test is difficult ordisabled.

Further, when the pogo pins are used, since there exists a contactresistance between each end of the pogo pins and each of the electrodesor since there are many contact portions due to the combination withsprings and balls, the total contact resistance is relatively large,with the result that there exists another problem in that apredetermined pulse waveform cannot be obtained. In addition, since thesignal pogo pins and the grounding pogo pins are used in the form ofpairs, the area occupied by a single pogo pin is relatively large, thusraising another problem in that it is difficult to mount the necessaryelements on the probe card at a high density.

Another embodiment of the probing device according to the presentinvention which can solve the above-mentioned problems will be describedhereinbelow with reference to FIGS. 4 to 6.

In FIG. 4, the same reference numerals have been retained for similarparts or elements which have the same functions as with the case of theembodiment shown in FIGS. 1 to 3. Over a wafer mounting base 1, acircular probe card 2 is provided so as to confront the wafer mountingbase 1. The probe card 2 is removably attached to a test head 6 via anintermediate connecting (aluminum block) body 5 (described later). Theprobe card 2 is composed of a flexible multilayer wiring substrate 43formed of polyamide, for instance and conductive projection bumps (i.e,contacts) 41 arranged on the lower surface of the multilayer wiringsubstrate 43. In this embodiment, the probe card 2 is also formed ofsilicon nitride at least on the lower surface side facing the wafer W,in the same way as with the case of the embodiment shown in FIGS. 2 and3.

These bumps 41 are also arranged in corresponding positionalrelationship with respect to all the electrode pads, so as to besimultaneously brought into contact with the electrode pads of all theIC chips formed on the wafer W. These bumps 41 are formed of gold of 18carats fine, tungsten, or nickel alloy, for instance. As shown in FIG.5, in the multilayer wiring substrate 43, a number of wiring layers 44used as conductive paths are laminated, and a plurality of groundinglayers 45 are formed on both upper and lower surfaces of the multilayerwiring substrate 43 and between the two adjacent wiring layers 44.

To the circumferential portion and on the upper surface side of theprobe card 2, a first annular conductive block body 8 formed ofaluminum, for instance is jointed. This first block body 8 is formedwith a number of through holes 81 passing from the upper surface to thelower surface thereof. Further, in this embodiment shown in FIG. 5, areinforcing insulating substrate 46 on both surfaces of which arecovered with copper foil is interposed between the multilayer wiringsubstrate 43 and the first block body 8.

Into each of these through holes 81, a conductive axle 82 whose diameteris smaller than that of the through hole 81 is inserted coaxially withrespect to the through hole 81 so as not to be in contact with the innercircumferential wall of the through hole 81. The lower end of theconductive axle 82 is passed through the multilayer wiring substrate 43and slightly projects from the lower surface of the substrate 43. Themultilayer wiring substrate 43 is formed with through holes 83 whoseinner circumferential walls are covered with a metallic (e.g., copper)foil. The conductive axle 82 is also passed through the through hole 83formed in the multilayer wiring substrate 43. The lower end of theconductive axle 82 is soldered to the metallic foil of the through hole83 of the multilayer wiring substrate 43. These through holes 83 arearranged so as to correspond to the bumps 41 in number, so that it ispossible to electrically connect the bumps 41 to the conductive axles82, respectively through the wiring layers 44 formed in the multilayerwiring substrate 43.

As depicted in FIG. 6, in a space between the through hole 81 and theconductive axle 82, an insulating body 84 formed of an insulatingmaterial (e.g., polypropylene) is interposed. This insulating body 84 isformed into such a female shape that a concave portion 85 is formed bycombination of both a reverse conical shape and a cylindrical shape.Further, the conductive axle 82 is formed into such a male shape thatthe upper end portion thereof projects within the concave portion 85 ofthe insulating body 84 and the tip thereof is mated with anotherconductive axle 92 (described later). By forming the coaxial structureas described above, it is possible to carry out the impedance matchingof the high frequency test signals used for probing test, so that thehigh frequency characteristics of the probing device can be furtherimproved.

On the other hand, as shown in FIG. 4, over the probe card 2, a testhead 6 serving as a part of the measurement section is supported by asupporting mechanism (not shown). On the lower surface side of the testhead 6, a wiring substrate 61 formed of an insulating material such asglass or epoxy resin is provided so as to face the probe card 2. Thiswiring substrate 61 is provided with a plurality of wiring layers 60(see FIG. 5) and grounding layers (not shown) in the same way as withthe case of the multilayer wiring substrate 43 of the probe card 2.

To the lower surface of the wiring substrate 61, a second annularconductive block body 9 formed of aluminum, for instance is jointed atsuch a position as to face the first block body 8. The junction surfacebetween the first and second block bodies 8 and 9 and the other junctionsurfaces between the first block body 8 and the probe card 2 and betweenthe second block body 9 and the wiring substrate 61 are all plated withgold. Further, the block body (9) side of the wiring substrate 61 iscovered with copper foil which is grounded.

In the same way as with the case of the first block body 8, this secondblock body 9 is formed with a number of through holes 91 incorresponding positional relationship with respect to the through holes81 of the first block body 8. Into each of the through holes 91, asimilar conductive axle 92 and a similar insulating body 94 areinserted. The upper end of the conductive axle 92 is passed through athrough hole 93 of the wiring substrate 61 and then soldered. Theinsulating body 94 is of male shape mated with the insulating body 84 offemale shape on the first block body (8) side. Further, the lower end ofthe conductive axle 92 is of female shape mated with the conductive axle82, as already explained.

The function of the above-mentioned embodiment will be describedhereinbelow. First, the probe card 2 is attached to the lower surfaceside of the wiring substrate 61 of the test head 6. In this attachment,the first block body 8 and the second block body 9 are opposed to eachother, and further the cylindrical insulating bodies 84 and 94 (in FIG.6) interposed in the through holes 81 and 91 are mated with each other.By this mating, it is possible to mate the conductive axles 82 and 92with each other securely for electrical connection. Further, both theblock bodies 8 and 9 are brought into surface contact with each other.In this case, although the conductive axles 82 and 92 are both enclosedby the block bodies 8 and 9, since both the block bodies 8 and 9 aregrounded, the conductive axles 82 and 92 can be electrically shielded.In addition, the bumps 41 are electrically connected to the test head 6via these conductive axles 82 and 92, respectively.

After that, a wafer W (an object to be inspected) is mounted on thewafer mounting base 1. Further, an optical position detecting instrument(not shown) is inserted between wafer mounting base 1 and the probe card2, and the wafer mounting base 1 is moved in the three directions of X,Y and θ with the use of the driving mechanism 12 to adjust the matchingposition of the wafer W relative to the probe card 2. Successively, thewafer mounting base 1 is raised to bring all the electrode pads of allthe IC chips formed on the wafer W into contact with the bumps 41arranged on the probe card 2 at the same time. In this case, when thebump (41) arrangement area is pushed from above by an appropriatepushing means such as springs or a damping body 52 (e.g., air mat orrubber body as shown by dot-dashed lines in FIG. 4), since the bumps 41can be connected to the chip electrode pads under the urged conditionscaused by a restoring force of the damping body 52, it is possible torealize a more reliable electrical contact between the bumps 41 and theelectrode pads. After that, predetermined test pulse signals are appliedfrom the test head 6 to the IC chips on the wafer W, and the test pulsesignals transmitted from the IC chips are received by the test head 6,in order to discriminate whether the IC chips are acceptable or not.

In this embodiment, since the probe card 2 and the wiring substrate 61disposed on the side of the test head 6 are electrically connected toeach other in perfect coaxial positional relationship with respect toeach other with the use of the conductive axles 82 and 92, it ispossible to keep constant the impedance of the conductive paths relativeto the ground, with the result that the waveforms of the high frequencytest signals of 1 GHz or higher are not distorted without beingsusceptible to the influence of the external noise. In addition, sincethe conductive axles 82 and 92 are all inserted into the through holes83 (of the multilayer wiring substrate 43) and 93 (of the wiringsubstrate 61) for connection between the respective wiring layers 44 ofthe probe card 2 and the respective wiring layers 60 of the wiringsubstrate 61 and further since the conductive axles 82 and 92 are bothmated with each other on the basis of coaxial male and female connectionrelationship, it is possible to reduce the contact resistance betweenthese connection portions markedly, as compared with the conventionalprobing device which uses pogo pins. As a result, when the IC chips areinspected by use of high frequency test pulse signals, high preciseelectrical measurements can be realized, thus coping with the test ofthe semiconductor IC chips whose operating speed is increasing more andmore.

Further, since the conductive axles 82 and 92 are enclosed by the blockbodies 8 and 9 formed of aluminum, it is unnecessary to fit a shieldingelectrode to the outer circumference of each of the conductive axles,individually, thus reducing the area required for one pin (one axle) ofthe block bodies 8 and 9 and thereby allowing a high density pinarrangement on the probe card. When the bumps are brought into contactwith all the electrode pads of all the IC chips formed on the wafer Wsimultaneously, since the number of the bumps is large, the structure ofthe above-mentioned embodiment is very advantageous. In addition, whenboth the block bodies 8 and 9 are joined to each other by mating theinsulating bodies 84 and 94 one another, it is possible to automaticallylocate the probe card 2 relative to the wiring substrate 61.

In the above-mentioned description, without being limited to only thebumps, it is also possible to use needles made of tungsten as thecontacts of the probe card. Further, without being limited to only thecontacts connectable to the electrode pads of all the IC chips formed onthe wafer simultaneously, it is also possible to use contacts of such atype as to be brought into contact with a part of the electrode pads ofthe IC chips in sequence.

Further, the block bodies can be made of a metal other than aluminum, orelse it is also possible to use the block bodies made of a conductiveplastic or of an insulating body covered with a metallic foil. Further,in the above-mentioned embodiment, the block body disposed between theprobe card 2 and the wiring substrate 61 of the test head 6 is dividedinto two. Without dividing the block body, it is also possible to adoptsuch a construction that the block body is fixed to one of the probecard and the wiring substrate in such a way as to be separable from theother of them.

In the above-mentioned embodiment, the conductive block bodies 8 and 9are interposed between the probe card 2 and the wiring substrate 61 ofthe test head 6, in such a way as to be brought into contact with thesubstrate surfaces of the probe card 2 and the wiring substrate 61.Further, the probe card 2 and the wiring substrate 61 are electricallyconnected to each other by the coaxial connecting structure provided inthe block bodies. Accordingly, the conductive paths can be shieldedwithout forming any gaps, so that it is possible to keep constant theimpedance of the conductive paths relative to the ground, with theresult that high precise electrical measurements and inspections can berealized for the semiconductor IC chips of high operating speed on thebasis of high frequency test pulse signals.

FIGS. 7 to 9B show another embodiment of the probing device according tothe present invention, in which means for securing the electricalcontact between the bumps and the electrode pads is additionallyprovided; that is, the contacts of the probe card (i.e., bumps) canbreak through an oxide film formed naturally on the electrode padsformed on the wafer W (an object to be inspected).

In this embodiment, the same reference numerals have been retained forthe similar parts or elements which have the same functions as with thecase of the afore-mentioned embodiments, without repeating any detaileddescription thereof. However, only the points different from theafore-mentioned embodiments will be explained in detail hereinbelow.

In FIG. 7, over the probe card 2, a plate 104 movable in the horizontaldirection is disposed. This movable plate 104 is formed with asquare-shaped cutout portion 141 at the middle portion thereof in such arange as to cover the arrangement area of bumps 41. Further, the movableplate 104 is formed with two slots 142 each having a length almostequivalent to the front-rear width (in a direction perpendicular topaper in FIG. 7) of the cutout portion 141, on both sides of the cutoutportion 141. In addition, over the movable plate 104, a printed circuitboard 105 having a reinforcing plate 133 on the lower surface of theboard 105 is fixed to an outer frame 150 of a device body (not shown).The reinforcing plate 133 is formed with two slots 134 on both sidesthereof at positions slightly outward from the slots 142 formed in themovable plate 104. In the same way, the printed circuit board 105 isformed with two slots 151 on both sides thereof at positions furtherslightly outward from the slots 142 and 134 formed in the movable plate104 and the reinforcing plate 133, respectively.

The probe card 2 is fixed to the lower surface of the movable plate 104in such a way that the bump (41) arrangement area can face the cutoutportion 141 formed in the movable plate 104. Further, both the right andleft flexible ends 131 of the probe card 2 are passed through the slots142 formed in the movable plate 104, through the slots 134 formed in thereinforcing plate 133 and further through the slots 151 formed in theprinted circuit board 105, respectively; turned in the outward directionon both sides thereof; and then fixed to the upper surface of theprinted circuit board 105, as depicted in FIG. 7. Both the end portions131 of the probe card 2 are each a multilayer wiring substrate having anumber of layers laminated as conductive paths electrically connected tothe bumps 41, respectively. In the multilayer wiring substrate,grounding layers set to a ground potential are formed on both the upperand lower surfaces thereof and interposed between the respective wiringlayers. The outer end contacts (not shown) of these wiring layers andthe grounding layers are connected to contacts 152 formed on the printedcircuit board 105.

Further, over the printed circuit board 105, a contact ring 162 isdisposed as an intermediate connecting body. The contact ring 162 isprovided with a plurality conductive pins (referred to as pogo pins) 161extensibly projecting in the vertical direction. The lower ends of thesepogo pins 161 are in contact with electrodes 153 electrically connectedto the contacts 152 of the printed circuit board 105 via printed wires,and the upper ends of these pogo pins 161 are in contact with electrodes(not shown) of a test head 6 disposed over the contact ring 162. Owingto these conductive paths, the test head 6 can be connected to the bumps41 electrically by way of the pogo pins 161, the printed circuit board105, and the multilayer wiring substrate 131, respectively.

A link mechanism having link arms 143 is provided between a mountingframe 154 attached to the lower surface of the reinforcing plate 133 andthe movable plate 104. These link arms 143 are pivotally supported onthe upper ends thereof by the mounting frame 154 and on the lower endsthereof by the movable plate 104, respectively. Therefore, the link arms143 can be moved along a circular arc locus described around two axesarranged in parallel to each other on the surface of the wafer W andexpanding toward the wafer mounting base (1) side, under the conditionthat the movable plate 104 is kept horizontally positioned.

To keep the probe card 2 away from the wafer W, the link arms 143 arekept at the oblique status (the movable plate 104 is shifted to eitherside), as shown in FIG. 7. In this case, the clockwise pivotal motionsof the link arms 143 about the mounting frame 154 are stopped by anappropriate stopper (not shown). Further, over the bump (41) arrangementarea of the probe card 2, there is provided damping means for urging thebumps 41 against the wafer W via the flexible multilayer wiringsubstrate 131, that is, a damping body 52 such as an air bag or a rubbermat fit between the probe card 2 and the printed circuit board 105.Further, the shape of the bumps 41 can be modified as shown in FIGS. 9Aand 9B.

The function of the probing device as described above will be describedhereinbelow. First, an object to be inspected (e.g., wafer W) isconveyed onto the wafer mounting base 1 with the use of conveying arms(not shown) and lift pins (not shown) incorporated within the wafermounting base 1. After that, the horizontal positions of the probe card2 and the wafer W are matched by inserting an optical detecting unitbetween the probe card 2 and the wafer W and by adjusting the X, Y and θdirections of the wafer mounting base 1 on the basis of the imagesdetected by the optical detecting unit. The optical detecting unit candetect both the images of the surface of the wafer W and the bump (41)arrangement surface of the probe card 2 at the same time.

Further, the wafer mounting base 1 is raised to bring the electrode padsof all the IC chips formed on the wafer W into contact with all thebumps 41 simultaneously. In this case, when the wafer mounting base 1 isfurther raised, since the damping body 52 is pressed, the bumps 41pushes the electrode pads of the wafer W via the flexible multilayersubstrate 131 by a restoring force of the damping body 52. In this case,since the movable plate 104 is moved both in the vertical and horizontaldirections through the link mechanism 143, the bumps 41 are shifted inthe horizontal direction being rubbed with the electrode pads.Therefore, the electrode pads of the wafer W are electrically connectedto the test head 6 via the bumps 41 by way of the already explainedpassage. Under these conditions, a predetermined supply voltage and testpulse signals are applied from the test head 6 to the IC chips formed onthe wafer W, and further the signals outputted by the test head 6 arereceived by the test head 6 to discriminate whether the IC chips areacceptable or not.

In the probing device according to the present invention, after thebumps 41 has been brought into contact with the electrode pads, sincethe bumps 41 are shifted in the horizontal direction under the conditionthat the surfaces of the electrode pads are pushed by the bumps 41, anoxide film naturally formed on each surface of each electrode pad can berubbed off and further broken away, so that it is possible to bring thebumps into reliable contact with the metal surfaces (e.g., aluminumsurface) of the electrode pads, thus enabling highly precisemeasurements on the basis of the further reliable electric contactbetween the bumps 41 and the electrode pads formed on the wafer W.

In the above description, as the mechanism for moving the probe card 2horizontally under the condition that the wafer W is being pusheddownward by the probe card 2, another driving mechanism other than abovecan be used such that a hard plate is disposed on the upper surface ofthe multilayer wiring substrate 131 (remote from the bumps 41) and,after the bumps 41 are brought into contact with the wafer W, the linkarms 143 are pivoted clockwise by another driving mechanism.Alternatively, it is also possible to support and move the wafermounting base 1 by the similar link mechanism, instead of moving theprobe card 2. Further, without providing any link mechanism, it is alsopossible to provide another mechanism for moving the wafer mounting base1 and the probe card 2 both in the horizontal direction relative to eachother. Further, it is also possible to move the wafer mounting base 1and the wafer W together relative to the bumps 41 in the X, Y or θdirection, by use of the driving mechanism 12 of the wafer mounting base1, after the wafer W have been brought into contact with the bumps 41.

Furthermore, without being limited to only the probe card 2 such thatthe bumps 41 are brought into contact all the electrode pads of thewafer W simultaneously, it is possible to use the probe card 2 ofpartial multi-contact type such that the bumps are brought into contactwith a part of the electrode pads. In this case, it is preferable tomove the wafer mounting base 1 in such a way that each group of thebumps 41 can be brought into contact with each group of the electrodepads in sequence. Further, the above-mentioned principle can be appliedto the probing devices of another type such that the wafer mounting baseis arranged in the vertical direction, without being limited to theprobing device provided with the horizontal wafer mounting base.

What is claimed is:
 1. A probing device, comprising:object mounting means for supporting an object to be inspected, having a silicon substrate with electrode pads; measuring means; a probe card having contacts electrically connected to said measuring means and arranged so as to face said object, said probe card being formed of silicon nitride at at least one surface thereof facing said object; supporting means for supporting a circumferential portion of said probe card; a wiring substrate connected to said measuring means and provided so as to face the probe card supported by said supporting means; connecting conductor means provided in a circumferential portion of the probe card and electrically connected to said contacts; means for moving said mounting means relative to said probe card so that the contacts can be brought into contact with the electrode pads of the object mounted on said mounting means; means for changing the temperature of the object; interim connecting means for electrically connecting said connecting conductor means to said wiring substrate, said interim connecting means including a first connecting means provided on a side of said probe card and a second connecting means provided on a side of the wiring substrate, said first and second connecting means being removably connected to each other, said first connecting means including a first block body formed with a first through hole, said second connecting means including a second block body formed with a second through hole which is coaxial with said first through hole; a first hollow insulating member fitted in said first through hole; a second hollow insulating member fitted in said second through hole; and a first conductive axle extending through said first insulating member and electrically connected to said connecting conductor means; a second conductive axle extending through said second insulating member and electrically connected to said wiring substrate; and said first and second conductive axles having mutually adjoining ends that are separably connected.
 2. The probing device of claim 1, wherein one of said mutually adjoining ends of the first and second conductive axles has a male shape and the other has a female shape, and the adjoining ends are joined removably by a male-female engagement.
 3. The probing device of claim 1, wherein said first and second insulating members have adjoining ends, respectively, one of the adjoining ends having a male shape and the other having a female shape, the male and female shapes being removably fitted.
 4. The probing device of claim 1, wherein said probe card is composed of a wiring substrate and a silicon nitride substrate fixed to the wiring substrate on the surface side thereof facing the inspected object; and the wiring substrate is formed with an insulating substrate and a conductive layer formed in parallel to a surface of the insulating substrate.
 5. The probing device of claim 1, wherein the insulating substrate is flexible.
 6. The probing device of claim 1, wherein the contacts are arranged on a surface of the silicon nitride substrate and connected to the conductive layer electrically.
 7. The probing device of claim 1, wherein said probe card includes at least one ground layer. 